Land structure for semiconductor package and method therefor

ABSTRACT

In one embodiment, a method for forming a package substrate includes selectively removing portions of a lead frame to form cavities and filling the cavities with a resin layer to define an adhesion pad and a land structure. Top portions of the lead frame are selectively removed to isolate the adhesion pad and the land structure from each other, to expose a top surface of the resin layer, and to form at least one land having a part with a relatively greater size than the size of a respective lower part.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to Korean Patent Application No.10-2012-0126438 filed on Nov. 9, 2012, which is expressly incorporatedby reference herein.

BACKGROUND

The present invention relates to electronic devices and, morespecifically, to electronic device package structures and methods offabricating the same.

Electronic devices, such as semiconductor dies, are conventionallyenclosed in plastic packages that protect the semiconductor die fromhostile environments and that enable electrical interconnection betweenthe semiconductor die and a next level of assembly, such as a printedcircuit board (PCB) or motherboard. The elements of a typical electronicpackage include a conductive leadframe or substrate, an integratedcircuit or semiconductor die, conductive structures, such as bond wiresor solder balls that electrically connect pads on the semiconductor dieto individual leads of the leadframe or substrate; and a hard plasticencapsulant material that covers the other components and forms anexterior of the semiconductor package commonly referred to as thepackage body. Portions of the individual leads can be exposed for use inelectrically connecting the package to the next level assembly.

Consumer electronics devices are continually getting smaller and, withadvances in technology, are gaining ever increasing performance andfunctionality. This is clearly evident in the technology used inconsumer electronic products such as smart phones, laptop computers,tablet devices, wearable devices, as well as other electronic devices.Requirements of the smart phone industry, for example, are drivingsemiconductor packaged components to become smaller with higherfunctionality and reduced cost. A micro lead frame (MLF) typesemiconductor package is one semiconductor package that is capable ofrealizing such a reduction.

In general, an MLF type semiconductor package is fabricated by forming alead frame having an adhesion pad and at least one land physicallyisolated from each other with a resin layer, adhering a semiconductordie to the adhesion pad, connecting the chip pad of the semiconductordie and the land using a conductive wire, and then encapsulating thesemiconductor die and the conductive wire with a molding member. Such aprocess is described in Korean Patent Laid-Open Publication No.2009-0069884 (published on Jul. 1, 2009).

One problem with prior MLF type semiconductor packages is that the landsbecame dislodged from the bottom surface of the package during eitherthe manufacturing of the package or subsequently during attachment ofthe package to a next level of assembly, such as a PCB. This greatlyreduced the reliability of MLF type semiconductor packages.

Accordingly, it is desirable to have a structure and method that improvethe reliability and functionality of small scale electronic packagessuch as MLF type semiconductor packages.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A to 1J illustrate cross-sectional views of an electronic packageat various stages of fabrication in accordance with an embodiment of thepresent invention;

FIGS. 2a to 2f illustrate perspective views of land structures havingvarious shapes that can be used in an electronic package in accordancewith an embodiment the present invention;

FIGS. 3A and 3B illustrate top and bottom views respectively of aportion of an electronic package in accordance with an embodiment of thepresent invention;

FIG. 4 illustrates a cross-sectional view of an electronic packagemanufactured in accordance with another embodiment of the presentinvention;

FIG. 5 illustrates a cross-sectional view of a land structure for anelectronic package in accordance with an additional embodiment of thepresent invention; and

FIGS. 6A to 6F illustrate cross-sectional views of a land structure atvarious stages of fabrication in accordance with a further embodiment ofthe present invention.

For simplicity and clarity of the illustration, elements in the figuresare not necessarily drawn to scale, and the same reference numbers indifferent figures can denote the same elements. Additionally,descriptions and details of well-known steps and elements are omittedfor simplicity of the description.

DETAILED DESCRIPTION OF THE DRAWINGS

The aspects of the present invention and methods for achieving theaspects will be apparent by referring to the embodiments to be describedherein with reference to the accompanying drawings. It is understoodthat the embodiments described herein are illustrative only and that thepresent invention is not limited thereto, but can be implemented inalternative forms.

In accordance with the present embodiments, a substrate for anelectronic package includes a land structure and an adhesion pad. Theland structure and the adhesion pad are isolated from each other using,for example, an insulating layer. In one embodiment, the insulatinglayer can be a resin material. In another embodiment, the insulatinglayer can be multiple layers of materials, which can be the samematerials or different materials. An electronic device, such as asemiconductor chip, can be attached to the adhesion pad and electricallyconnected to the land structure. In one embodiment, the electronicdevice and portions of the substrate are encapsulated with a mold body.

In accordance with the present embodiments, the land structure includeslands with a first portion having a relatively greater size than asecond portion. In one embodiment, the first portion is proximate to anupper surface of the substrate. In another embodiment, the first portionis proximate to a middle portion of the substrate. In a furtherembodiment, the first and second portions can have the same shape. In astill further embodiment, the first and second portions can havedifferent shapes. In accordance with one embodiment, the adhesion padincludes a first portion having a relatively greater size than a secondportion. In one embodiment, the first portion of the adhesion pad isproximate to an upper surface of the substrate. In one embodiment, thefirst portion of the adhesion pad is proximate to a substantiallycentrally located portion of the substrate. In a further embodiment, thefirst and second portions of the adhesion pad can have the same shape.In a still further embodiment, the first and second portions of theadhesion portion can have different shapes. The resultant packagestructure provides, among other things, improved locking features andovercomes other disadvantages of prior structures and methods. It isunderstood that the features of the various embodiments described hereincan be combined with each other, unless specifically noted otherwise.

FIGS. 1A to 1F illustrate cross-sectional views of an electronic packageat various stages of fabrication in accordance with a first embodiment.In one embodiment, the electronic package is configured as an MLF typesemiconductor package. In FIG. 1A, a portion of a lead frame orsubstrate 102 is selectively removed by performing a half-etchingprocess using, for example, photoresist patterns (not shown) as an etchbarrier or protective layer, to form holes or cavities 104 a extendinginward from a bottom surface or lower surface of lead frame 102. In thepresent embodiment, cavities 104 a are configured to physically isolatean adhesion pad and lands (to be formed through subsequent processes)from each other. In one embodiment, lead frame 102 can be made of aconductive material, such as copper (Cu), aluminum (Al), alloys thereof,plated materials, combinations thereof, or other materials known tothose of ordinary skill in the art.

FIG. 1B illustrates the electronic package after additional processing.For example, the remaining photoresist patterns can be removed (orstripped), and a filling process is then performed so that cavities 104a are filled with an insulating material. In one embodiment, theinsulating material can be one or more resin materials, such as an epoxymold compound (EMC), thereby forming resin layers 104 in cavities 104 a.In one embodiment, resin layer 104 can be formed by over-fillingcavities 104 a with the resin material such that the resin materialoverlaps onto the surface of lead frame 102 adjoining cavities 104 a,and then removing excess resin material outside of cavities 104 athrough a grinding process or an etch-back process until the bottom ofthe lead frame is exposed proximate to cavities 104 a. In oneembodiment, portions of lead frame 102 may also be removed or portionslead frame 102 can act as a stop layer. In one embodiment, resin layer104 is substantially co-planar with the bottom surface of lead frame 102as generally illustrated in FIG. 1B.

FIG. 1C illustrates the electronic package after more processing. Forexample, photoresist patterns 106 are formed at desired or predeterminedlocations (that is, top regions on lead frame 102, each pattern 106 forphysically isolating an adhesion pad and lands to be formed throughsubsequent processes from each other) on the top surface or uppersurface of lead frame 102 by coating a photoresist or masking materialon lead frame 102, and then performing exposure and developmentprocesses.

FIG. 1D illustrates the electronic package after further processing. Forexample, plating materials or conductive materials 108 a can be formedon the top and bottom of lead frame 102 by performing, for example, aplating process using photoresist patterns 106 formed on the top surfacelead frame 102 as plating-shield or protective layers. For example, asillustrated in FIG. 1E, plating layers 108 can be formed on the top andbottom of lead frame 102 by removing (or stripping) the remainingphotoresist patterns 106 before the plating process is done.

FIG. 1F illustrates the electronic package after still furtherprocessing. For example, masking layers such as photoresist patterns 110are formed on exposed surfaces of the plating layers 108 and surfaces ofthe resin layers 104 by coating photoresist materials on both surfacesof lead frame 102 and then performing exposure and developmentprocesses. In the present embodiment, photoresist patterns 110 defineopenings on the top surface of lead frame 102 to expose portions of leadframe 102 for physically isolating an adhesion pad and lands to beformed through subsequent processes.

The exposed top regions of lead frame 102 can then be removed byperforming an etch process or half-etch process using photoresistpatterns 110 as etch barrier layers. This step can form an opening orcavity extending inward from the top regions of lead frame 102. In oneembodiment, the etch process continues until part of the top surface ofresin layer 104 is exposed in the opening formed. For example, asillustrated in FIG. 1G, the etching process forms lands 102 b, eachhaving the size of the upper part relatively larger than the size of thelower part, and an adhesion pad 102 a (also having the size of the upperpart relatively larger than the size of the lower part thereof) to whichan electronic chip, such as a semiconductor die, can be attached. In asubsequent step, the remaining photoresist patterns can be removed.

In accordance with the present embodiment and illustrated in FIG. 1G, aplurality of land structures 102 b (or lands), which are physicallyisolated from each other and from adhesion pad 102 a, and eachconfigured to have the size of the upper part relatively larger than thesize of the lower part, can be formed in the lead frame by performing aseries of the processes as set forth hereinbefore. The structures of theupper part and the lower part of land structures 102 b manufacturedaccording to the present embodiment can have various shapes such asrectangular shapes or circular shapes. In another embodiment, the upperpart of land structures 102 b can be a rectangular shape and the lowerpart thereof can be a circular shape. In a further embodiment, the upperpart of land structure 102 b can be a circular shape and the lower partthereof can be a rectangular shape.

FIGS. 2a to 2f illustrate perspective views of land structures havingvarious shapes that can be used with embodiments of the electronicpackage described in accordance with FIGS. 1A to 1G. FIG. 2a illustratesa land structure where both upper part 202 a and lower part 202 b havegenerally rectangular shapes. FIGS. 2b and 2c illustrate a landstructure where upper parts 204 a and 206 a have generally rectangularshapes and lower parts 204 b and 206 b thereof have generally circularshapes. In FIG. 2c , side portions of lower part 206 b are inset fromupper part 206 a and other sidewall portions of lower part 206 b areflush with side portions of upper part 206 a. FIG. 2d illustrates a landstructure where both upper part 208 a and lower part 208 b have agenerally rectangular shape with lower part 208 b having side portionsinset on only two sides of upper part 208 a. FIG. 2e illustrates a landstructure where upper part 210 a has a generally rectangular shape, thelower part 210 b thereof has a generally circular shape, and lower part210 b has side portions inset on only two sides of upper part 210 a.FIG. 2f illustrates a land structure where upper part 212 a has agenerally circular shape and lower part 212 b thereof has a generallyrectangular shape with the four corners of lower part 212 b beingsubstantially flush with the side portions of upper part 212 a. Adhesionpad 102 a can be formed, for example, having the various shapecombinations described above or other shapes.

FIGS. 3A and 3B are top and bottom views respectively of a packagesubstrate 300 illustrating a structure having land structures configuredhaving upper parts or portions that are relatively larger in sizecompared to the lower part thereof in accordance with one embodiment. Asillustrated in FIGS. 3A and 3B, upper part 304 a of the land structurehas a generally rectangular shape and has a relatively larger size thanthe size of lower part 304 b thereof. FIGS. 3A and 3B further illustratean adhesion pad 302, which is configured for attaching an electronic dieor semiconductor die thereto. Additionally, FIG. 3B illustrates theindividual lands and adhesion pad 302 isolated from each other by aresin layer, such resin layer 104 illustrated in FIG. 1G.

Referring now back to FIG. 1H, an adhesive or attachment layer (notshown), such as a solder paste, can be coated on or over the top surfaceof adhesion pad 102 a. In one embodiment, a screen print method can beused to form the adhesive layer. Next, an electronic device or chip,such as a semiconductor die 112, is attached to adhesion pad 102 a, anda bonding process is then performed, thereby connecting (electricallyconnecting) chip pads or bond pads 114 on semiconductor die 112 and thelands 102 b using, for example, conductive wires 116. Accordingly, forexample and as illustrated in FIG. 1I, electrical bonding or connectionbetween semiconductor die 112 and lands 102 b is facilitated.

FIG. 1J illustrates the electronic package after further processing. Forexample, as illustrated in FIG. 1J, a molding member, mold body, orencapsulating layer 118 for protecting or encapsulating semiconductordie 112 and conductive wires 116 is formed by performing, for example amold process to encapsulate (or mold) semiconductor die 112 andconductive wires 116 with a material (or molding member) such as amolding compound.

In the present embodiment, chip pads 114 on semiconductor die 112 andlands 102 b have been illustrated as being coupled by conductive wires116 and the conductive wires have been illustrated as being used aselectrical connecting members between the semiconductor die and thelands, but the present embodiment is not necessarily limited thereto.For example, FIG. 4 illustrates a cross-sectional view of an electronicpackage manufactured in accordance with another embodiment. In FIG. 4,reference numeral 402 b corresponds to 102 b of FIG. 1J, referencenumeral 414 corresponds to 112 of FIG. 1J, reference numeral 418corresponds to 118 of FIG. 1J, and 402 b, 414, and 418 can have thesimilar structures and materials as 102 b, 112, and 118, respectively.

As illustrated in FIG. 4, semiconductor die 414 and lands 402 b can beelectrically (or physically) connected by connecting members (orconductive bumps) 410, such as solder balls or Kappa fillers. Ifsemiconductor die 414 and lands 402 b are interconnected by conductivebumps (or connecting members), such as solder balls or Kappa fillers,not by conductive wires, a MLF type substrate (for example, acombination of an adhesive pad, lands, and a resin layer) can befabricated without performing processes related to plating in theelectronic package of the present embodiment. Additionally, thisembodiment can provide an electronic package with a smaller height orlower profile.

FIG. 5 illustrates a cross-sectional view of a land structure for anelectronic package, such as a semiconductor package, in accordance withanother embodiment. In one embodiment, the land structures illustratedin FIG. 5 can be configured for connecting with the chip pads of anelectronic device or chip (for example, a semiconductor device), whichcan be attached to an adhesion pad, through connecting members (forexample, conductive wires, solder balls, or Kappa fillers). Asillustrated in FIG. 5, a land 502 can be defined by or encapsulated by afirst mold layer 506 configured to have a generally curved surface shapeand a second mold layer 516 configured to have a generally curvedsurface shape and that can make contact with the first mold layer 506.

Land 502 is further defined by a cross-sectional area CS3 proximate toan internal part, a middle part, or a substantially centrally locatedpart 518 c of land 502 and is configured to be relatively larger thaneach of a cross-sectional area CS1 in a lower part 518 a of land 502 anda cross-sectional area CS2 in an upper part 518 b of land 502. In oneembodiment, first mold layer 506 can be a pre-mold layer (for example, apre-mold filled in a substrate fabrication process), and second moldlayer 516 can be an epoxy mold compound (“EMC”) mold layer. That is,first mold layer 506 and second mold layer 516 can be formed usingdifferent methods and/or different materials. Furthermore, the pre-moldlayer is not limited to a pre-mold material, and various types ofresins, such as epoxy or prepreg, can be used as the pre-mold layer.

In one embodiment, the shape of land 502 as described herein can beobtained by forming a first hole having curved surface form or shape onone side of a lead frame and forming a second hole in a curved surfaceform or shape on the opposite side of the lead frame. In one embodiment,the first hole and the second hole can be formed having curved surfacesby using a pressure difference (for example, fast etch rate versus slowetch rate) in the etchant coming in contact with respective portions ofthe lead frame during a half-etching process. In another embodiment,each of the first hole and the second hole can be formed having curvedsurfaces using a pressure difference and adjusting the etching time ofthe etchant that comes into contact with respective portions of the leadframe during a half-etching process. In one embodiment, the holeconnected in a roundabout manner and having a curved surface shape canbe formed using a half-etching process in such a way as to applyrelatively strong etching pressure to the center of part of the leadframe corresponding to the hole and apply gradually weaker etchingpressure to the sides around the center.

In one embodiment, surfaces lower part 518 a, middle part 518 c, andupper part 518 b of land 502 that are generally perpendicular to thecurved surfaces of the first and second holes can have a generallyquadrangular shape (or a rectangular shape). In another embodiment,these parts can have a generally circular shape. In one embodiment,middle part 518 c can have a relatively larger cross-sectional area thaneach of lower part 518 a and upper part 518 b, which provides aconfiguration that provides a locking structure or lock jaw that reducesthe likelihood that land 502 will detach from the mold layers of thepackage substrate. Furthermore, a neck part 518 d can be formed betweenthe middle part 518 c and the lower part 518 a. In the presentembodiment neck part 518 d is configured to have a cross-sectional areaCS4 that is relatively smaller than the cross-sectional area CS1 oflower part 518 a. In one embodiment, neck part 518 d can be formed usingan etchant having a relatively greater etching diffusion property towardthe sides of the holes than etching in a direction generally parallel tothe sides thereof when performing the half-etching process. In thepresent embodiment, neck part 518 d can function as an additionallocking structure for reducing the likelihood that land 502 will detachfrom the molding layers of the package substrate. In FIG. 5, referencenumeral 510 is illustrated as an optional plating layer. Plating layer510 can be formed as a thin film on the bottom surface and/or the topsurface of the land 502, and can comprise a solderable material.

FIGS. 6A to 6F illustrate cross-sectional views of land structures atvarious stages of fabrication in accordance with one embodiment. Theland structures are configured for use in an electronic package, such asan MLF type semiconductor package. Referring to FIG. 6A, first holes orcavities 504, which are configured to have a curved surface shape and tophysically isolate lands to be formed through subsequent processes fromeach other, are formed by selectively removing part of or portions ofone surface, such as the bottom surface, of a lead frame or substrate502 a through a half-etching process using photoresist patterns (notshown) as etch barrier layers. The lead frame 502 a can be made of aconductive material, such as, copper (Cu), aluminum (Al), alloysthereof, plated materials, combinations thereof or other materials knownto those of ordinary skill in the art.

In one embodiment, first holes or cavities 504 can be formed having acurved surface by using a pressure difference of an etchant that comesinto contact with part of the bottom surface of lead frame 502 a or apressure difference and etching time of an etchant that comes in contactwith part of the bottom surface of lead frame 502 a. More particularly,first hole 504, which is connected in a roundabout manner in a curvedsurface form, can be formed using a half-etching process in such a wayas to apply relatively strong etching pressure towards the center ofpart of the bottom of lead frame 502 a in which first hole 504 will beformed and to apply gradually weaker etching pressure to the sidesaround the center.

In one embodiment, an etchant having a relatively greater lateraletching diffusion property toward the sides of the hole than etchingvertical or inward when performing the half-etching process can be usedsuch that the cross-sectional area CS4 of the neck part of the land isrelatively smaller than the cross-sectional area CS1 of the lower part.In one embodiment, a combination or series of anisotropic and isotropicetchants can be used to form first hole 504.

Next, after removing (stripping) the remaining photoresist patterns,first hole 504 can be filled or over-filled with resin materials byperforming a filling process, and the excess resin materials can thenremoved by performing a grinding process or another removal process. Inone embodiment, the resin materials can overlap onto the surface of leadframe 502 a adjoining first hole 504. In one embodiment, the resinmaterials are planarized until the bottom surface of lead frame 502 a isexposed, thereby forming first mold layer 506 having the resin materialsfilled in first hole 504 as illustrated, for example, in FIG. 6B. In oneembodiment, first mold layer 506 can be a pre-mold layer includingmaterials described previously.

FIG. 6C illustrates the land structure after additional processing. Forexample, photoresist patterns 508 can be formed at desired orpredetermined locations on the upper surface of lead frame 502 a (thatis, top regions on lead frame 502 a, each pattern 508 for physicallyisolating the lands) by coating photoresist materials on lead frame 502a and then performing exposure and development processes.

FIG. 6D illustrates the land structure after more processing. Forexample, optional plating materials can be selectively formed on the topand bottom of lead frame 502 a by performing a plating process usingphotoresist patterns 508 formed on the lead frame 502 a asplating-shield or protective layers. For example, as illustrated in FIG.6D, plating layers 510 are formed on the top and bottom of lead frame502 a by removing (or stripping) the remaining photoresist patterns 508before the plating process is done.

FIG. 6E illustrates the land structure after further processing. In oneembodiment, photoresist patterns 512 can be formed on plating layers 510by coating photoresist materials on lead frame 502 a on which theplating layers 510 have been formed and then performing exposure anddevelopment processes. In the present embodiment, the top regions oflead frame 502 a, each for physically isolating lands to be formedthrough subsequent processes from each other, are exposed throughphotoresist patterns 512.

As further illustrated in FIG. 6E, second holes 514, each configured tohave a curved surface shape and to physically isolate lands to be formedthrough subsequent processes from each other, can be formed byselectively removing part of the top of lead frame 502 a using ahalf-etching process with photoresist patterns 512 as etch barrierlayers. In one embodiment, second holes or cavities 514 can be formedhaving a curved surface by using a pressure difference of an etchantthat comes into contact with part of the top surface of lead frame 502 aor a pressure difference and etching time of an etchant that comes intocontact with part of the top surface of lead frame 502 a. Moreparticularly, second hole 514, which is connected in a roundabout mannerin a curved surface form, can be formed using a half-etching process insuch a way as to apply relatively strong etching pressure to the centerof part of the top surface of lead frame 502 a at which a hole will beformed and applying gradually weaker etching pressure toward the sidearound the center.

Next, after removing (stripping) the remaining photoresist patterns 512,second hole 514 can be filled or over-filled with resin materials byperforming a filling process, and the excess resin materials can beremoved by performing a grinding process or another removal process. Inone embodiment, the resin materials are planarized until the top surfaceof lead frame 502 a is exposed, thereby forming the second mold layer516 having the resin materials filled in second holes 514 asillustrated, for example in FIG. 6F. Here, second mold layer 516 can beconfigured as an EMC mold layer.

In accordance with the present embodiment, land 502 is formed havinginternal part 518 c that has a relatively greater cross-sectional areathan both lower part 518 a and upper part 518 b. Furthermore, thepresent embodiment provides neck part 518 d between internal part 518 cand lower part 518 a that has a relatively smaller cross-sectional areathan lower part 518 a.

In accordance with the present embodiment, the land structure for anelectronic package can be manufactured in such a way as to form aninternal part thereof having a relatively greater cross-sectional areathan each of a lower part and an upper part. The internal part thereofis buried, covered or encapsulated with, for example, a pre-moldmaterial. In a subsequent step, an electronic device, such as asemiconductor die, is attached to an adhesion pad within the lead frameand electrically connected to the land structure with connectivedevices. The semiconductor die and the connective devices areencapsulated with a molding member. In one embodiment, the pre-mold andthe molding member may be different materials, and the connective devicecan be any one of a conductive wire, a solder ball, a Kappa filler, orcombinations thereof. Accordingly, a land locking effect is obtainedwhen fabricating an electronic package, such as an MLF typesemiconductor package, even without changing the sizes of a land on theupper and lower parts.

In the present embodiment, the first mold layers (for example, layers506) are formed and the plating layers are then formed on portions ofthe top and bottom surfaces of the lead frame by performing a platingprocess; however, the present embodiment is not necessarily limitedthereto. The plating process for forming the plating layers may beomitted, if necessary, or it may be performed after second mold layers(for example, layers 516) are formed.

In accordance with another embodiment, the land structure of anelectronic package, which is electrically connected with a chip pad of asemiconductor die adhered to an adhesion pad by means of a couplingmember, is configured to have the size of the upper part of the landrelatively larger than the size of the lower part thereof. Accordingly,a land locking effect is obtained when fabricating an electronicpackage, such as an MLF type semiconductor package.

From all of the foregoing, one skilled in the art can determine that,according to one embodiment a land structure for a semiconductor packagecomprises a land coupled with a chip pad of a semiconductor die, whichis adhered to an adhesion pad, through a coupling member, wherein a sizeof an upper part of the land is relatively larger than a size of a lowerpart of the land.

In one embodiment of the foregoing structure, each of the upper part andthe lower part of the land can have a rectangular structure. In anotherembodiment, each of the upper part and the lower part of the land canhave a circular structure. In an additional embodiment, the upper partof the land can have a rectangular shape and the lower part of the landcan have a circular shape. In a further embodiment, the upper part ofthe land can have a circular shape and the lower part of the land canhave a rectangular shape.

From all of the foregoing, one skilled in the art can determine that,according to another embodiment a method for manufacturing asemiconductor package comprises forming an adhesion pad and lands, eachhaving a size of an upper part relatively larger than a size of a lowerpart, in a lead frame, the adhesion pad and the land are physicallyisolated from each other by an insulating layer such as a resin layer.The method includes attaching a semiconductor die to the adhesion pad.The method includes electrically coupling chip pads of the semiconductordie and the lands. The method includes forming a molding member forburying the semiconductor die and conductive wires.

In one embodiment of the foregoing method, electrically coupling thechip pads and the lands can be performed using one of conductive wires,solder balls, or Kappa fillers. In another embodiment, forming theadhesion pad and the lands can comprise forming the insulating layer fordefining the adhesion pad and the land in the lead frame; forming aplating layer through which a top region for separating the adhesion padand the land is selectively exposed; and forming the adhesion pad andthe land by removing the exposed top region using an etching process sothat part of a top surface of the insulating layer is exposed. In afurther embodiment, forming the insulating layer can comprise forming acavity by selectively removing part of the lead frame using an etchingprocess; filling the cavity with insulating materials; and uniformlyremoving the insulating materials using a grinding process so that abottom region of the lead frame is exposed. In a still furtherembodiment, forming the plating layer can comprise forming aplating-shield layer in the top region; forming the plating layers on atop and bottom of the lead frame using a plating process; and removingremaining plating-shield layers. In additional embodiment, theplating-shield layer can be a photoresist pattern.

From all of the foregoing, one skilled in the art can determine that,according to an additional embodiment an electronic package can comprisean electronic die adhered to an adhesion pad. A land is physicallyisolated from the adhesion pad and configured to have a size of an upperpart of the land relatively larger than a size of a lower part of theland. A coupling member electrically connects the electronic die and theland. A molding member encapsulates the electronic die and the couplingmember.

In one embodiment of the foregoing package structure, each of the upperpart and the lower part of the land can have a rectangular structure. Inanother embodiment, each of the upper part and the lower part of theland can have a circular structure. In an additional embodiment, theupper part of the land can have a rectangular shape and the lower partof the land can have a circular shape. In a further embodiment, theupper part of the land can have a circular shape and the lower part ofthe land can have a rectangular shape. In a still further embodiment,the coupling member can be one of a conductive wire, a solder ball, or aKappa filler.

From all of the foregoing, one skilled in the art can determine that,according to a further embodiment an electronic package comprises anelectronic die coupled to an adhesion pad. A land is proximate to theadhesion pad and has an internal part with a cross-sectional area largerthan a cross-sectional area of each of a lower part and an upper partthereof, the land further having a part under the internal partencapsulated with a pre-mold. A coupling device electrically connectsthe electronic die to the land. A molding member covers the electronicdie and the coupling device.

In one embodiment of the foregoing package structure, each of the lowerpart, the internal part, and the upper part of the land can have acircular shape. In another embodiment, the internal part functions as alocking jaw of the land. In an additional embodiment, each of the lowerpart and the internal part, and the upper part and the internal part canbe connected in a curved surface form. In a further embodiment, thecoupling device can be a conductive wire, a solder ball, or a Kappafiller.

From all of the foregoing, one skilled in the art can determine that,according to a still further embodiment a method of forming a packagesubstrate comprises forming a first hole having a curved surface shapeby selectively etching part of a first surface of a substrate. Themethod includes forming a first insulating layer in the first hole. Themethod includes forming a second hole of a curved surface by selectivelyetching part of a second surface of the substrate. The method includesforming a second insulating layer in the second hole.

In one embodiment of the foregoing method, forming the first hole cancomprise forming the first hole using a pressure difference of anetchant that comes into contact with part of the lower part. In anotherembodiment, forming the first hole can comprise applying relativelystrong etching pressure to a center of part of the lower partcorresponding to the first hole and applying gradually weaker etchingpressure to a side around the center. In an additional embodiment,forming the first hole can comprise forming the first hole using apressure difference and etching time of an etchant that comes intocontact with part of the lower part. In a further embodiment, formingthe first hole can comprise using an etchant having a relatively greatetching diffusion property to a side of the first hole. In a stillfurther embodiment, forming the first insulating layer can compriseforming resin materials to cover the first hole and planarizing thefirst mold layer so that a surface of the substrate is exposed. In yetanother embodiment, the planarizing step can be done with a grindingprocess. In another embodiment, forming the second hole can compriseforming the second hole using a pressure difference of an etchant thatcomes into contact with part of the top. In an additional embodiment,forming the second hole can comprise applying relatively strong etchingpressure to a center of the top corresponding to the second hole andapplying gradually weaker etching pressure toward a side around thecenter. In a further embodiment, forming the second hole can compriseforming the second hole using a pressure difference and etching time ofan etchant that comes into contact with part of the top. In a stillfurther embodiment, forming the second insulating material can comprisecovering the second hole, wherein the method provides a land having amiddle part whose cross-sectional area is relatively larger than across-sectional area of each of a lower part and a upper part byuniformly removing the second insulating so that a surface of thesubstrate is exposed.

In view of all the above, it is evident that a novel structure andmethod are disclosed. Included, among other features, is a landstructure embedded within a resin or insulating layer. In oneembodiment, the land structure has an upper part that relatively largerthan the size of the lower part. In another embodiment, an internal partof the land structure is relatively larger than both the upper and lowerparts of the land structure. The land structures are configured toprovide an improved locking feature and to further improve interconnectand assembly processes.

While the subject matter of the invention is described with specificpreferred embodiments and example embodiments, the foregoing drawingsand descriptions thereof depict only typical embodiments of the subjectmatter and are not, therefore, to be considered limiting of its scope.It is evident that many alternatives and variations will be apparent tothose skilled in the art.

As the claims hereinafter reflect, inventive aspects may lie in lessthan all features of a single foregoing disclosed embodiment. Thus, thehereinafter expressed claims are hereby expressly incorporated into thisDetailed Description of the Drawings, with each claim standing on itsown as a separate embodiment of the invention. Furthermore, while someembodiments described herein include some but not other featuresincluded in other embodiments, combinations of features of differentembodiments are meant to be within the scope of the invention and formdifferent embodiments, as would be understood by those skilled in theart.

What is claimed is:
 1. A method for forming an electronic packagecomprising: providing a substrate having an adhesion pad and a land, theland having a first part proximate to a first surface of the substrate,a second part proximate to a second surface of the substrate and a thirdpart between the first part and the second part, wherein each of thefirst, second, and third parts has a cross-sectional area, and whereinthe cross-sectional area of the third part is larger than thecross-sectional areas of each of the first part and the second part, andwherein at least a portion of the first part is encapsulated with afirst insulating layer, and wherein at least a portion of the secondpart is encapsulated with a second insulating layer, and wherein theland further comprises a fourth part between the first part and thethird part, and wherein the fourth part has a cross-sectional areasmaller than the first part, and wherein the fourth part is configuredto provide a locking structure; coupling an electronic die to theadhesion pad adjacent the second surface and the land; and encapsulatingat least portions of the electronic die with a mold member.
 2. Themethod of claim 1, wherein providing the substrate comprises providingthe substrate wherein the first insulating layer and the secondinsulating layer comprise different materials, and wherein the land islaterally separated from the electronic die.
 3. The method of claim 2,wherein providing the substrate comprises providing the substratewherein the first insulating layer comprises a pre-mold material, andwherein the second insulating layer comprises an epoxy mold compoundlayer.
 4. The method of claim 1, wherein providing the substratecomprises: forming a first hole of a first curved surface shape byselectively etching part of a first surface of the substrate; formingthe first insulating layer in the first hole; forming a second hole of asecond curved surface shape by selectively etching part of a secondsurface of the substrate; and forming the second insulating layer in thesecond hole.
 5. The method of claim 4, wherein forming the firstinsulating layer comprises over-filling the first hole with the firstinsulating layer such that the first insulating layer overlaps the firstsurface of the substrate, and wherein the method further comprisesplanarizing the first insulating layer.
 6. The method of claim 1,wherein providing the substrate comprising providing the first part andthe second part having different shapes.
 7. The method of claim 1,wherein coupling the electronic die to the adhesion pad comprisingattaching using one of a conductive wire, a solder ball, or a Kappafiller.
 8. A method for forming an electronic package comprising:providing a substrate having a land, the land having a first partproximate to a first surface of the substrate, a second part proximateto a second surface of the substrate, and a third part between the firstpart and the second part, wherein the first part has a first width in across-sectional view, the second part has a second width in thecross-sectional view, and the third part has a third width in thecross-sectional view, and wherein the third width is larger than thefirst width and the second width, and wherein at least a portion of thefirst part is encapsulated with a first insulating layer, and wherein atleast a portion of the second part is encapsulated with a secondinsulating layer, and wherein the land further comprises a fourth partbetween the first part and the third part, wherein the fourth part has afourth width in the cross-sectional view, and wherein the fourth widthis smaller than the first width; coupling an electronic die to the landwith a connecting member, wherein the electronic die has a first majorsurface and a second opposing major surface, and wherein the first majorsurface overlaps and faces the land, and wherein connecting member isbetween the first major surface and the land; and encapsulating at leastportions of the electronic die with a mold member.
 9. The method ofclaim 8, wherein providing the substrate comprises providing thesubstrate wherein the first insulating layer and the second insulatinglayer comprise different materials, and wherein coupling the electronicdie comprises coupling the electronic die with one or more of a Kappafiller or a solder ball, and wherein encapsulating includesencapsulating such that the mold member is adjacent the connectingmember and both the first and second major surfaces of the electronicdie such that a portion of the mold member is between the first majorsurface and the land.
 10. The method of claim 8, wherein providing thesubstrate comprises: providing a first hole of a first curved surfaceshape by selectively etching part of a first surface of the substrate;providing the first insulating layer in the first hole; providing asecond hole of a second curved surface shape by selectively etching partof a second surface of the substrate; and providing the secondinsulating layer in the second hole.
 11. The method of claim 10, whereinproviding the first insulating layer comprises over-filling the firsthole with the first insulating layer such that the first insulatinglayer overlaps the first surface of the substrate, and wherein themethod further comprises planarizing the first insulating layer.
 12. Themethod of claim 8, wherein providing the substrate comprises providingthe first part and the second part having different shapes.
 13. A methodfor forming an electronic package comprising: providing a substratehaving an adhesion pad and a land, the land having a first partproximate to a first surface of the substrate, a second part proximateto a second surface of the substrate, a third part between the firstpart and the second part, and a fourth part between the third part andfirst part, wherein each of the first, second, third and fourth partshas a cross-sectional area, and wherein the cross-sectional area of thethird part is larger than the cross-sectional areas of each of the firstpart and the second part, and wherein the cross-sectional area of thefourth part is less than the cross-sectional area of the first part, andwherein at least a portion of the first part is encapsulated with afirst insulating layer, and wherein at least a portion of the secondpart is encapsulated with a second insulating layer; coupling anelectronic die to the adhesion pad adjacent the second surface and theland; and encapsulating at least portions of the electronic die with amold member.
 14. The method of claim 13, wherein providing the substratecomprises providing the substrate wherein the first insulating layer andthe second insulating layer comprise different materials.
 15. The methodof claim 13, wherein providing the substrate comprises providing theland laterally spaced apart from the electronic die.
 16. The method ofclaim 13, wherein providing the substrate comprises: providing a firsthole of a first curved surface shape by selectively etching part of afirst surface of the substrate; providing the first insulating layer inthe first hole; providing a second hole of a second curved surface shapeby selectively etching part of a second surface of the substrate; andproviding the second insulating layer in the second hole.
 17. The methodof claim 16, wherein providing the first insulating layer comprisesover-filling the first hole with the first insulating layer such thatthe first insulating layer overlaps the first surface of the substrate,and wherein the method further comprises planarizing the firstinsulating layer.
 18. The method of claim 13, wherein providing thesubstrate comprises providing the first part and the second part havingdifferent shapes.